666624421 has 16 divisors (see below), whose sum is σ = 705801600. Its totient is φ = 628669888.

The previous prime is 666624419. The next prime is 666624437. The reversal of 666624421 is 124426666.

It is not a de Polignac number, because 666624421 - 2¹ = 666624419 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666624121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 284571 + ... + 286903.

It is an arithmetic number, because the mean of its divisors is an integer number (44112600).

Almost surely, 2^666624421 is an apocalyptic number.

It is an amenable number.

666624421 is a deficient number, since it is larger than the sum of its proper divisors (39177179).

666624421 is a wasteful number, since it uses less digits than its factorization.

666624421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2588.

The product of its digits is 82944, while the sum is 37.

The square root of 666624421 is about 25819.0708779383. The cubic root of 666624421 is about 873.5620118520.

The spelling of 666624421 in words is "six hundred sixty-six million, six hundred twenty-four thousand, four hundred twenty-one".